Which of the following types of energy transfers can take place when matter is not present

Question

A. heat
B. conduction
• C. radiation
• D. convection

Answer 1

C. radiation

Radiation is the only type of energy transfer that can occur in a vacuum, where matter is not present. It involves the transfer of energy through electromagnetic waves, such as light, which can travel through empty space.

In contrast, conduction and convection both require matter to transfer heat. Conduction relies on direct contact between materials, while convection depends on the movement of fluids (liquids or gases).

Answer 2

Javier made a list about balanced and unbalanced forces.
Balanced Forces
Unbalanced Forces
• can cause an object to speed up, slow down, or change directions
• cause objects to stay in the same place or to continue moving at the same speed
Javier made a mistake on his list. Which best describes the mistake Javier made?
• A. Javier forgot to add that forces can never change.
• B. Balanced forces only cause objects to change directions.
• C. Unbalanced forces only cause objects to stay in the same place.
D. Javier switched the descriptions for unbalanced and balanced forces.

Answer 3

D. Javier switched the descriptions for unbalanced and balanced forces.

In his list, the descriptions for balanced and unbalanced forces are incorrectly assigned. Balanced forces do cause objects to stay in the same place or continue moving at the same speed, while unbalanced forces can cause an object to speed up, slow down, or change directions.

Answer 4

When the index card is quickly pulled away from a glass in a horizontal direction, why does the disk fall straight down into the glass?
A. equilibrium
B. static friction
C. kinetic friction
D. inertia

Answer 5

D. inertia

When the index card is quickly pulled away, the disk remains in place for a moment due to inertia, which is the tendency of an object to resist changes to its state of motion. The disk, having no net horizontal force acting on it when the card is pulled away quickly, continues to move in the direction it was last traveling (which is downwards due to gravity) and falls straight down into the glass.

Answer 6

A student is investigating mass and acceleration. The student applies the same force to two boxes, as shown in the table.
Box
Force
Applied to Box (newtons)
Acceleration (meters/second?)
1
20
5
2
20
2
The student claims that box 1 must have a smaller mass than box 2. Which argument BEST supports the student's claim?
• A. Heavier objects require less force than lighter objects to accelerate at the same rate.
B. Heavier objects require greater force than lighter objects to accelerate at the same rate.
C. Lighter objects require less force than heavier objects to start moving but will accelerate at the same rate.
D. Lighter objects require greater force than heavier objects to start moving but will accelerate at the same rate.

Answer 7

B. Heavier objects require greater force than lighter objects to accelerate at the same rate.

This argument best supports the student's claim because, according to Newton's second law of motion (F = ma), if the same force is applied to two different boxes and they have different accelerations, the one that accelerates less (box 2) must have a greater mass. Therefore, box 1, which has a higher acceleration under the same force, must have a smaller mass than box 2.

Answer 8

Read the passage about an investigation.
A student is performing an investigation in which she wraps a current-carrying wire around an iron rod. She places the north pole of a bar magnet near the top of the rod. The magnet moves away from the rod. The student claims that a field exists between the rod and the magnet.
Which argument best supports her claim?
•
A. The current in the wire has created a magnetic field with its north pole at the top of the rod.
B. The current in the wire has created a magnetic field with its south pole at the top of the rod.
C. The current in the wire has created a gravitational field with its north pole at the top of the rod.
• D. The current in the wire has created a gravitational field with its south pole at the top of the rod.

Answer 9

A. The current in the wire has created a magnetic field with its north pole at the top of the rod.

This argument supports the student's claim because when a current-carrying wire is wrapped around an iron rod, it generates a magnetic field. If the north pole of the magnet is near the top of the rod and the magnet moves away, it indicates that there is a magnetic interaction happening. Specifically, if the current in the wire creates a magnetic field with its north pole at the top of the rod, then that would create a repulsive force between the north pole of the bar magnet and the north pole of the induced magnetic field in the rod, leading to the observed movement.